My brother played Rifts and AD&D when he was teen and I was wee. I couldn't join in, thus I read the Rifts book cover-to-cover, yet have never roleplayed it, and have always wanted to until hearing the aforementioned groans.

By my memory, it certainly did strike me that there were distinct worlds - MD and SD - and it seemed that any successful game had to sort of "choose" one to play in, where the other side would be mostly-externalized color.

Indeed, that seemed to be how power-scaling worked too. You simply couldn't all pick your classes independently - some sense had to be made within the party itself (are you military, adventurers, hoodlums, urban, monstrous, etc). Based on that, the Core alone seemed to have enough material to completely encapsulate several different possible settings, which still seems impressive to me.

My question: has anyone found a simplified version of the mechanics that they've enjoyed, or that works well for them?

I'm Ron. I've split your post into its own thread and I greatly hope this does not make you feel like an insect pinned to a board and shined upon with a bright light. It's merely my way, as moderator, of preserving threads' chronological identity. I do appreciate that experience at other forums leads people to want to join existing conversations as a form of courtesy. Here, that's not necessary. Instead, the courtesy is something you can expect as a given from the others who are already here.

Your post is a fine rock-solid topic. It would be a bit more helpful if you added some account, however sketchy, of something you have played to reinforce your point. Especially your final question: it leads me to infer that you haven't found mechanics that match that description, and I don't want my inference to be "real" until you confirm it or let me know that's not right. The best way to do that is to describe your experience with some game's mechanics which either does simplify certain Rifts principles, or does not. Long experience here has led me to the conclusion that we'll understand you best that way - especially what you mean by "simplify," which is a difficult word in our hobby subculture.

Given that play-based clarification on your part, there are a lot of Rifts veterans posting here who I'm sure will be able to hop right in.

I've never heard of Palladium publishing a simplified rules text for Rifts.

My experience accords with your impressions exactly. When I played, we used all MD all the time, with a few exceptions:

1) Any SD stuff we liked from the books we brought in as non-combat elements. Nothing to prevent an SD critter from tricking you, or holding your mom hostage, or negotiating on behalf of someone more powerful, etc.

2) SD could become relevant in special scenes, like where your regular joe finally stepped out of his giant mech armor and was suddenly vulnerable to stuff like knives and pistols.

We found "MD with exceptions" way more fun than having SD characters utterly dwarfed any time we wanted to use an MD element. For what it's worth, playing MD wasn't difficult; nothing in the game relies on an SD presence.

I suspect Kevin Siembieda simply held a tight social grip on his game group, along the lines of "Your character IS outside his armour now" Player: "Oh, okay". Where in another group, as the texts do not describe lines of authority/chains of command that make the game work in some way, the player might go "WTF, who's playing my character, me or you? No, he's not out of his armour!" and the SDC scene frame suddenly fails. The usual 'The author didn't write down how he actually plays' problem.

I always envisioned it as being a case of situation determining how you handled RIFTS SD/MD mechanics. I mean you were unlikely to have MD when you were on foot running around inside of an enemy base that you approached while inside of your MD-capable unit . . .

But again, some people need things spelled out, and others do not. Probably best to go from the standpoint of explaining, just in case. :)

you were unlikely to have MD when you were on foot running around inside of an enemy base that you approached while inside of your MD-capable unit

One must prevent, then, laser-pistols being used inside the base. My thought is simply the old rule of Aliens - don't fire pulse rifles when directly underneath the facility's fusion reactor. Of course, it ended up taking a giant helicopter-thing crashing to actually break it down, but the point is the same.

In other words, while the outside of the base may have MD armor, you probably shouldn't fire a plasma beam indoors with plaster or even brick walls and linings without severe structural consequences.

It doesn't prevent, though. Players don't understand the difference between A: A fictionally described hurdle which is there as a reason X can't currently happen in play and B: A fictionally described hurdle which is there for the players to creatively overcome, or atleast try to.

Players wont understand the difference unless it said not with fiction but with actual explicit instructions. They will start figuring ways around the 'don't fire under the fusion reactor', whether it means vibro blades or whatever. I had a game not so long ago where the GM described a crack in the wall of a base that was too tight to get through in armour. Okay, we said, we take off our armour, slide through, then the other guy hands us our armour, piece by piece, in to us. Then we put it back on. It didn't make us not wear our armour while exploring the abandoned base - we just ended up an overcome hurdle. I'm not sure why the GM did it.

That's why I suspect Kevin Sembieda simply had a capacity to say "Your not wearing your armour now" and it was accepted, yet he didn't realise that's how he got the two modes of MDC and SDC to work, so he didn't write it in that a GM can just declare at some point your out of your metal skin.